Photographic layers for the silver dyestuff bleaching method



United States Patent 3,211,554 PHOTOGRAPHIC LAYERS FOR THE SILVER DYESTUFF BLEACHING METHOD Paul Dreyfuss, Basel, Switzerland, assignor to Ciba Corporation, a corporation of Delaware No Drawing. Filed July 11, 1961, Ser. No. 123,092 Claims priority, application Switzerland, July 22, 1960, 8,382/ 60 Claims. '(CI. 96-99) "The silver dyestutf bleaching method for the production of photographic images depends on the fact that numerous azo-dyestuifs, with which a layer forming material, especially gelatine, is colored can be destroyed to an extent which depends on the quantity of image silver present by the action of suitable dyestuif bleaching baths by the reduction of the azo-linkage.

The present invention provides photographic layers suitable for the silver dyestutf bleaching method which are colored with an azo-dyestuif of the formula OH in in which X represents a hydrogen atom or a sulfonic acid group, X represents a sulfonic acid group or sulfonic acid amide group, R represents a cyclic radical containing at least one benzene ring to which the azolinkage is bound, and A represents an acylamino group bound to the radical R by its nitrogen atom.

As will be seen from the formula the dystutfs contain at least one sulfonic acid group. The dyestufls molecule advantageously contains two to four acid groups imparting solubility in water, which groups include sulfonic acid groups and carboxylic acid groups. X, represents either a sulfonic acid group or advantageously a hydrogen atom. X represents a sulfonic acid group, or it may represent a sulfonic acid amide group more especially when X represents a hydrogen atom. X may be an unsubsbtituted sulfonic acid amide group or a sulfonic acid amide group substituted at the nitrogen atom having the formula R1 S0m in which R represents an alkyl radical which may be substituted, for example, by hydroxyl groups, or repre- S0311 in sents an aryl radical, especially a phenyl radical, or a cycloalkyl radical such as cyclohexyl, or an aralkyl radical such as benzyl, R represents a hydrogen atom or an alkyl radical which may be substituted, or R and R may together with the nitrogen atom represent a heterocyclic radical, for example, a morpholine radical. The radical R is a cyclic radical which contains at least one benzene ring, and the azo-linkage is bound directly to the benzene ring. In addition to the acylamino group, the radical R may contain further substituents, for example, lower alkyl or alkoxy groups such as methyl, ethyl, methoxy or eth- QZMQ L -Q l oxy, or a halogen atom such as chlorine, or a sulfonic acid or carboxylic acid group.

The acylamino group A is advantageously derived from a carboxylic acid of high molecular weight, for example, a fatty acid containing -12 to 22 carbon atoms. However, the acylamino group may be of more complex constitution by being derived, for example, from cyanuric acid, or being a benzeneor toluene-sulfonyl amino group or an acylamino group of the constitution -SO benzene nucleus NHCO- alkyl radical. In general it is of advantage when the acylamino group and the azo-linkage are bound to the benzene radical in para-position relatively to one another. As examples there may be mentioned dyestuffs of the formula OH HOa S OH HO in which X and X each represent a sulfonic acid group or advantageously a hydrogen atom, and X and X each represent a sulfonic acid group or a sulfonic acid amide group, R and R each represent a cyclic radical containing at least one benzene ring to which the azowlinkage is bound, for example, a monocyclic benzene radical bound in the metaor para-position to the azo-linkage, and A represents a radical of a diamide of an at least dibasic organic acid bound to R and R through the nitrogen atoms.

Such dyestuffs may be asymmetrical or advantageously symmetrical like the diazo-dyestulfs of the formula A EH H N X;

| HOaS HO- in which X and X have the meanings given above, It represents the whole number 1 or 2, and

represents the radical of a diamide of a dibasic acid. Radical A or A" may be derived, for example, from an aromatic dicarboxylic acid, such as isophthalic acid, terephthalic acid, 1:1'-diphenyl-3:3'- or -4:4'-dicarboxylic acid, or from a heterocyclic dicarboxylic acid such as furane-ZzS-dicarboxylic acid or an aliphatic dicarboxylic acid such as fumaric acid or butadiene dicarboxylic acid.

Especially valuable are those dyestuffs of the Formula 4 in which the radical NH "HN-- has the formula -NH-COHN.

Some of the dyestuffs of the Formulae 1 to 4 are known. The new dyestuffs of those formulae can be made by methods in themselves known.

An especially advantageous method is to couple an appropriate diazo-compound of the benzene series with 2- amino 8 -hydroxynaphthalene-6-sulfonic acid or a 2- amino 8 hydroxynaphthalene-6-sulfonic acid amide or Z-amino-8-hydroxynaphthalene-3:6-disulfonic acid in an acid medium.

As diazo components there are advantageously used nitroaminobenzenes, in which case a dyestuff of the Formulae 1 or 2 is obtained by reducing the nitro group and acylating the resulting amino group. The same dyestuffs can be obtained by using as diazo-compounds the corresponding monoacyl-phenylenediamine. Alternatively, the acyl radical, for example, the acetyl radical, may be split 01f from the monoazo-dyestuff so obtained and exchanged for another acyl radical, for example, the 4-nitrobenzoyl radical.

Diazo-dyestuffs of the Formula 4 can be made by linking together two molecules of amino-monoazo-dyestuffs in which the amino group is bound to the benzene radical by reaction with a dichloride of one of the aforesaid dibasic acids, reaction with phosgene being preferred.

Instead of the symmetrical urea derivatives obtainable with phosgene (or a mixture of asymmetrical and symmetrical urea derivatives, obtainable by reacting phosgene with a mixture of amino-azo-dyestufrs), unitary asymmetrical urea derivatives of the Formula 3 [in which A in this case represents a NHCOHN group] may be made by way of the phenyl-urethanes obtainable from amino-azo-dyestufrs and phenyl isocyanate.

As examples of diazo-components to be used for making the dyestuffs by the methods described above there may be mentioned the following compounds:

3- or 4-nitro-1-aminobenzene, 3-methy1-4-nitro-l-aminobenzene, 4-nitro-l-aminobenzene-Z-sulfonic acid, 1-amino-2-methoxy-4-nitrobenzene, 1-amino-2-methoxy 4-nitro-6-chlorobenzene, 1-aminoe2-methoxy-4mitrobenzene-S-sulfonic acid, 1-amino-Z-methoxyl-nitrobenzene-S-carbonic acid, l-amino-2 5-dimethoxy-4nitrobenzene, 1-amino-4-acetylaminobenzene-Z-sulfonic acid and 1-amino- 4-(4'-nitrobenzoylamino)-benzene-2-sulfonic acid In accordance with the invention the dyestuffs of the Formulae 1 to 4 are used for making colored photographic layers, especially gelatine layers, and also layers of other colloids used in the photographic art. These dyestuffs are used more especially for the purple image of a color photographic original or copying material, that is to say, in color negative materials or any color diapositives to be viewed by transmitted or reflected light. The layer forming material colored with such a dyestuff is mixed with a sliver halide emulsion, the silver halide is sensitized in the appropriate manner for a desired region of the spectrum and the resulting photographic layer is used, for example, as a component of a two-color or three-color system. Alternatively, a non-colored silver halide layer may be colored with the dyestuff after exposure and development, and then subjected to the dyestuff bleachi g process. The color image produced by the 4 silver dyestuff bleaching method may also be used for a transfer process or an imbibition process.

As dyestuff bleaching baths there are suitable most of the known neutral or acid, and especially the strongly acid bleaching baths which contain a solvent for silver, such as thiourea, urea or semicarbazide, and also an alkali metal halide, such as sodium or potassium chloride, bromide or iodide or an ammonium halide. Furthermore, the known catalysts such as anthraquinone and sulfonic acids thereof or dimethyl-quinoxaline or phenazines, used in the dyestuff bleaching baths for the azo-dyestuffs generally have an accelerating action on the dyestuff bleaching process.

It has been found that layers rich in silver lead to dyestuff images having excellent flat gradations. The silver of the image not consumed in the dyestuff bleaching process is converted into silver halide in known manner by means of an oxidizing bath in the presence of an alkali metal halide, for example, potassium ferricyanide and potassium bromide or by means of an acid bath containing copper sulfate and sodium chloride. Finally the image is fixed in known manner by means of a sodium thiosulfate bath, washed and dried.

The bleaching process may be further assisted by intermediate washings, for example, the image may be bleached for 10 minutes, washed in water for 5 minutes, again bleached for 10 minutes, washed for 5 minutes and finally bleached. The addition of a water-soluble organic solvent such as an alcohol, acetone, dioxane, glycol or dextrose, can be used to assist the bleaching process.

Dyestuffs that are sparingly soluble in water are incorporated in a micro-dispersed form in the gelatine. It is of advantage to use dyestuffs which are soluble in water or in an organic solvent which, like alcohol, acetone or dioxane, can easily be washed out of the gelatine.

The occasionally blackish tints of dyestuffs that are sparingly soluble in water can be brightened by modifying the substratum, for example, by adding a small proportion of a higher polyethylene glycol to the gelatine.

The photographic images obtained with the dyestuffs of the Formula 1 are distinguished by their very good fastness to light and this property is not or is only slightly impaired by substances that inhibit diffusion, such as guanidine, biguanide or triphenyl-guanidine, in the colored layer itself or in layers adjacent thereto.

The following examples illustrate the invention the parts and percentages being by Weight:

Example 1 3 to 5 grams of the dyestuff of the formula so rr H N SOaH are dissolved in 600 cc. of water. The aforesaid dyestuff is known and can be produced by coupling diazotized 1-amino-4-nitro-benzene-2-sulfonic acid with 2- amino-8-hydroxynaphthaline-6-sulfonic acid in an acid medium, reducing the resulting nitro-monoazo-dyestuff to the aminoazo-dyestuff and linking together two molecules of the dyestuff at the amino groups by means of phosgene to form the urea derivative. The solution is added to 1000 grams of a green sensitized silver bromide gelatine emulsion which contains 25 to 35 grams of silver, and one of the substances inhibiting diffusion which are referred to above is added. The quantity of dyestuff and the quantity of silver bromide may vary within the aforesaid limits depending on whether a transparency or an: image to be viewed by reflected light is to be made and' on the thickness of the layer.

The colored silver bromide gelatine emulsion is cast.

on a support, that is to say, on paper or a film, as a component of a 3-layer material. After drying the layer and exposing it, the negative silver image is developed with a solution containing, per liter or water, one gram hydroxyphenazine. The material is then washed in water for 5 minutes. The unconsumed image silver is converted into silver bromide by means of a bath containing, per liter of water, 60 grams of copper sulfate, 80 grams of of methyl-para-aminophenol, three grams of hydroqui- 5 potassium bromide and 30 cc. of hydrochloric acid of none, 25 grams of sodium sulfite, 40 grams of sodium car- 37% strength, and the material is Washed with water, bonate, 1 gram of potassium bromide. The duration of and the silver bromdie is dissolved by treating the mathe development is 5 to 7 minutes. The material is then terial for about 5 minutes in a fixing bath which contains washed in water for one minute, and then fixed for 5 200 grams of sodium thiosulfate per liter of water. Fiminutes in a bath containing, per liter of water, 200 10 nally the material is Washed with water for a further 5 grams of sodium thiosulfate and 25 grams of potassium minutes and dried. There is obtained a reverse image meta-bisulfite. After a fixing period of 5 minutes, the having a pure purple tint of very good fastness to light. material is again washed with water for 5 to 7 minutes, and then the gelatine is hardened for 5 minutes in an Example 2 aqueous solution of formaldehyde of 4% strength. The material is again washed for 5 minutes and then treated The p h 15 the Same as described 111 Example for minutes in a silver dyestuff bleaching bath which P that, Instead Of the dyestl1fi of h Formula contains in solution, per liter of Water, to 100 grams there 15 used one of the dyestuffs glven Column I of of potassium bromide 30 to grams of thiourea, 40 to the following table. In column II is given the tint procc. of hydrochloric acid of 37% strength and as a 2 duced by the dyestuff and in column 111 the wave length catalyst 1 cc. of a solution of 1% strength of 2-amino-3- at which the dyestuff has a maximum absorption.

II III No. I. Formula Tint Amax.

17H: HaC-O 1 N=N --NH-C O-CH: Purple 520 OH (|)CH3 Hoa s 2 N=NONH-oom Reddish 522 purple. 0 OH HOaS Hoa s Purple. 525 3 O OH HOaS HOQIS i 4 N=NG-NH-(fll-OKJHaho-Cfli Red 515 I O OH HOaS HO h NEG-803E NH Purple 528 5 N=NNH-C-NHO N ll O N=O OH 801K I I ENG-303E HOaS IOI a gN=NQNHfi-OH Purp1e 522 OH HQQS 110313 "See footnotes at end of table.

See footnotes at end of table.

II III No. 1. Formula Tint A max.

H038 NH, H21? SiO H O --OH HO 110 's S O H 1 Blaekish, without a wetting agent. 2 Also a maximum at 570. 3 Somewhat blackish.

What is claimed is: 1. A photographic silver halide emulsion layer for the silver dyestuff bleaching process, which layer is colored with an azodyestuff of the formula NH H N l NH A HN r 1 Li) J 1 I ('il l nn-l 0H Hogs 50311 HO HOa S S OaH in which A represents a member selected from the group consisting of the radicals of the formulae 3 if I? 30 =d=-, *"C==-'C'H=0H;G-* 3. A photographic silver halide emulsion layer for the and silver dyestufi bleaching process, which layer is colored with an azodyestuff of the formula and n represents a Whole number of at the most 2.

S|O3H 2. A photographic silver halide emulsion layer for the silver dyestufi bleaching process, which layer is colored in which n represents a whole number of at the most 2.

with an azodyestuff of the formula NH N l a NH A HN I n Li t n-l. 11- OH HOaS SOaH 11.0-- X: 951 in which X represents a member selected from the group consisting 'of a' sulfonic 'acid group and "a sulfonic acid amide group, A represents a member selected from the group consisting of the radicals of the formulae 60 E H E 4. A photographic silver "halide emulsion layer for the -CCH=CH silver dyestuff bleaching process, whichlayer is colored and with the azo dyestufl of the formula and n represents a whole number of at the most 2.

1 H 0 3S 0 S O 3 HZN H038 SOQH 13 14 5. A photographic silver halide emulsion layer for the silver dyestuff bleaching process, which layer is colored with the azo dyestuff of the formula OH H038 OH E038 References Cited by the Examiner UNITED STATES PATENTS 2,294,892 9/42 Carroll et a1 96-99 OTHER REFERENCES Okubo et 211.: Chemical Abstracts, vol. 48, pages 10,646-7 (1954).

NORMAN G. TORCHIN, Primary Examiner.

HAROLD N. BURSTEIN, Examiner. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSIN LAYER FOR THE SILVER DYSTUFF BEACHING PROCES, WHICH LAYER IS COLORED WITH AN AZODYESTUFF OF THE FORMULA 